Anti-jerk control method for electric vehicle

ABSTRACT

An anti-jerk control method for an electric vehicle incorporates an anti-jerk function that can be performed more accurately and effectively by utilizing a real-time weight change of an electric vehicle. The anti-jerk control method includes: estimating vehicle weight by a controller based on vehicle driving information collected from a vehicle; determining a required torque command of a driver by the controller based on the vehicle driving information collected from the vehicle; determining anti-jerk torque according to the vehicle weight based on calculated speed deviation and the estimated vehicle weight information; and controlling a drive motor according to a compensated motor torque command by compensating the required torque command with the anti-jerk torque in the controller.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims under 35 U.S.C. § 119(a) the benefit ofKorean Patent Application No. 10-2020-0062173, filed May 25, 2020, theentire contents of which are incorporated by reference herein.

BACKGROUND (a) Technical Field

The present disclosure generally relates to an anti-jerk control methodfor an electric vehicle, more particularly, to the anti-jerk controlmethod in which a weight change of the electric vehicle driven by amotor is utilized to perform anti-jerk control more accurately andeffectively.

(b) Description of the Related Art

As is known, an electric vehicle (EV) is a vehicle (a motorized vehicleor a motor-driven vehicle) that is driven by a motor as the source (adriving source) of a driving force for driving the vehicle.

A drivetrain of the electric vehicle includes: a battery that suppliespower to drive the motor; an inverter connected to the battery to driveand control the motor; the motor as a driving source connected to thebattery through the inverter such that the battery can be charged anddischarged; and a reduction gear that decelerates a rotational force ofthe motor and transmits the decelerated rotational force to a drivewheel.

The inverter functions to convert a direct current (DC) supplied fromthe battery during motor drive into an alternating current (AC), toapply the AC to the motor through a power cable, and to convert analternating current generated by the power generation operation of themotor during motor regeneration into a direct current so that the directcurrent is supplied to the battery so as to charge the battery.

Such an electric vehicle is vulnerable to surge in a low-speed regiondue to the characteristics of the system thereof, so anti-jerktechnology is applied to alleviate this surge.

In an electric vehicle, as a damping element is excluded or becomessmaller, during tip-in/out (stepping on or off an accelerator pedal),vibration such as shock and jerk (a momentary and rapid movement) occursalong with vibration of a drive shaft, which causes a reduction in ridecomfort and drivability.

Also, in the electric vehicle, since the damping element existingbetween the motor which is a torque source and the drivetrain isexcluded or is small, vibration from the torque source or vibration fromthe outside is not decreased.

To solve such a problem, anti-jerk control technology which suppressesvibration by using an anti-jerk torque calculated relative to a modelspeed to control a motor torque output is known.

According to such an anti-jerk control method, when a vehicle startsagain after stopping, anti-jerk control is performed by a controller, sothe surge of a motor speed and the jerk of the drivetrain that may occurin the initial stage of vehicle departure can be reduced.

In the case of a commercial electric vehicle as a motorized commercialvehicle such as an electric truck or an electric bus, a change in thetotal weight of the vehicle due to passengers or loads is greater thanthat of a passenger electric vehicle.

As such, when the total weight of a vehicle is large, various behaviorcharacteristics are changed. When the total weight of a vehicle ischanged even on the same road surface, at the same speed, and in thesame environmental condition, surge characteristics transmitted to adriver are also changed.

Anti-jerk control of an electric vehicle was first applied to apassenger electric vehicle. Since the amount of the total weight changeof a vehicle according to the number or load of passengers is not largein the passenger electric vehicle, differentiation according to vehicleweight is not required during the anti-jerk control.

Alternatively, since the amount of total vehicle weight change is greatin the commercial electric vehicle, the amount of the total vehicleweight change must be taken into consideration. However, conventionally,only an anti-jerk function developed based on no load condition isknown.

As loads on a vehicle increase, the characteristics of the vehicle maybe changed, and thus the surge characteristics of the vehicle may alsobe changed accordingly. Since the existing anti-jerk function isperformed based on the condition in which a vehicle is not loaded, it isdifficult to effectively reduce surges in the commercial electricvehicle.

Accordingly, in the commercial electric vehicle, an effective anti-jerktechnology performing anti-jerk function in consideration of the changeof total weight thereof is required.

SUMMARY

Accordingly, the present disclosure proposes an anti-jerk control methodfor an electric vehicle, in which an anti-jerk function can be performedmore accurately and effectively by utilizing the real-time weight changeof the electric vehicle when the electric vehicle is driven by a motor.

In order to achieve the above objective, according to an embodiment ofthe present disclosure, there is provided an anti-jerk control methodfor an electric vehicle, the method including: estimating vehicle weightby a controller based on vehicle driving information collected from avehicle; determining a required torque command of a driver by thecontroller based on the vehicle driving information collected from thevehicle; determining anti-jerk torque according to the vehicle weightbased on calculated speed deviation and the estimated vehicle weightinformation after calculating the speed deviation between a model speedand an actual speed of a motor in the controller; and controlling adrive motor according to a compensated motor torque command bycompensating the required torque command with the anti-jerk torque inthe controller.

Accordingly, according to the anti-jerk control method of the presentdisclosure, in a commercial electric vehicle, it is possible to moreeffectively alleviate surges in various conditions by performing adifferentiated anti-jerk control according to the weight of a vehicle inconsideration of changes in the weight of the vehicle.

Particularly, according to the present disclosure, in a commercialelectric vehicle such as a bus or truck with large change in the numberof passengers and the weight of loaded cargo, total vehicle weight isaccurately estimated in real time, and then the estimated weight isaccurately reflected to perform the anti-jerk control, therebymaximizing a surge suppression effect.

In addition, according to the present disclosure, surge vibration of acommercial electric vehicle may be reduced, thereby reducing a driver'sfatigue and improving the safety of cargo.

Further, according to the present disclosure, a non-transitory computerreadable medium containing program instructions executed by a processorincludes: program instructions that estimate vehicle weight based onvehicle driving information collected from a vehicle; programinstructions that determine a required torque command of a driver basedon the vehicle driving information collected from the vehicle; programinstructions that determine anti-jerk torque according to the vehicleweight based on calculated speed deviation and the estimated vehicleweight information after calculating the speed deviation between a modelspeed and an actual speed of a motor; and program instructions thatcontrol a drive motor according to a compensated motor torque command bycompensating the required torque command with the anti-jerk torque.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description when taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a block diagram illustrating the configuration of a systemperforming an anti-jerk control process according to the presentdisclosure; and

FIG. 2A and FIG. 2B are a flowchart illustrating the anti-jerk controlprocess according to the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g., fuels derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example bothgasoline-powered and electric-powered vehicles.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. Throughout the specification, unless explicitly describedto the contrary, the word “comprise” and variations such as “comprises”or “comprising” will be understood to imply the inclusion of statedelements but not the exclusion of any other elements. In addition, theterms “unit”, “-er”, “-or”, and “module” described in the specificationmean units for processing at least one function and operation, and canbe implemented by hardware components or software components andcombinations thereof.

Further, the control logic of the present disclosure may be embodied asnon-transitory computer readable media on a computer readable mediumcontaining executable program instructions executed by a processor,controller or the like. Examples of computer readable media include, butare not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes,floppy disks, flash drives, smart cards and optical data storagedevices. The computer readable medium can also be distributed in networkcoupled computer systems so that the computer readable media is storedand executed in a distributed fashion, e.g., by a telematics server or aController Area Network (CAN).

Hereinafter, an embodiment of the present disclosure will be describedin detail with reference to the accompanying drawings so that thoseskilled in the art to which the present disclosure belongs can easilypractice the embodiment. However, the present disclosure is not limitedto the embodiment described herein, but may be embodied in other forms.

As described above, in a commercial electric vehicle such as a bus ortruck, the number of passengers and the weight of loaded cargo may besignificantly changed during vehicle driving, so anti-jerk controltechnology in which the total weight change of the vehicle is taken intoconsideration is required.

To this end, in the commercial electric vehicle in which the totalweight change of a vehicle is large, it is necessary to accuratelydetect a current vehicle weight in real time and to perform anti-jerkcontrol according to the current vehicle weight.

The present disclosure is characterized in that after the total weightof a vehicle during driving is accurately estimated in real time, theestimated total vehicle weight is reflected to perform the anti-jerkcontrol.

Accordingly, when the anti-jerk control is performed according to thetotal weight of a vehicle, surges in various conditions can beeffectively alleviated, and a surge suppression effect can be maximized.

In the following description, vehicle weight refers to the total weightof a vehicle in which the weight of passengers or the weight of cargo isadded to the weight of the vehicle when the passengers are present orthe cargo is loaded therein.

FIG. 1 is a block diagram illustrating the configuration of a systemperforming an anti-jerk control process according to the presentdisclosure, and, along with an anti-jerk control system, shows a drivemotor 41 driving a vehicle, a reduction gear 42 reducing the rotationalforce of the to motor 41 and transmitting the reduced rotational force,and a drive wheel 43 rotated by the rotational force of the motortransmitted by the reduction gear 42.

The anti-jerk control process according to the present disclosure may beperformed by the cooperative control of a plurality of controllersprovided in a vehicle. However, the anti-jerk control process may beperformed by one integrated control element. In the followingdescription, the anti-jerk control process is performed by thecooperative control of a first controller 20 and a second controller 30.

In the following description, a control subject is divided into thefirst controller 20 and the second controller 30. However, it can beunderstood that the plurality of controllers or the integrated controlelement is commonly referred to as a controller, and the anti-jerkcontrol process according to the present disclosure is performed by thecontroller.

FIGS. 2A and 2B are a flowchart illustrating the anti-jerk controlprocess according to the present disclosure. While the configuration ofthe system in FIG. 1 is described, the anti-jerk control process will bedescribed with reference to FIGS. 2A and 2B.

Referring to FIG. 1, the anti-jerk control system according to thepresent disclosure includes the first controller 20 estimating thevehicle weight from a vehicle driving information collected from avehicle during driving, and the second controller 30 preforming theanti-jerk control according to the vehicle weight by using the vehicleweight information estimated by the first controller 20.

In the present disclosure, the first controller 20 may be a vehiclecontrol unit (VCU) that determines and generates a required torquecommand of a driver from the vehicle driving information and outputs therequired torque command.

In the present disclosure, the first controller 20 calculates therequired torque command of the driver in real time based on drivinginput information of the driver and vehicle state information of thevehicle driving information determined during vehicle driving, andestimates the vehicle weight in real time to transmit the calculatedrequired torque command and the estimated vehicle weight to the secondcontroller 30.

In addition, in the present disclosure, the second controller 30 may bea motor control unit (MCU) that operates an inverter with a motor torquecommand and controls the motor 41.

In a normal electric vehicle, a controller performing the anti-jerkcontrol is the motor control unit. After the motor control unitdetermines anti-jerk torque, the required torque command received by thevehicle control unit is compensated with the anti-jerk torque, and themotor is controlled with the compensated motor torque command.

However, in the present disclosure, the second controller 30 (forexample, a motor control unit) is provided to receive the estimatedvehicle weight information from the first controller 20 (for example, avehicle control unit) and to perform the anti-jerk control according tothe vehicle weight.

In the present disclosure, known weight estimation methods may be usedfor vehicle weight estimation. Many vehicle weight estimation methods ofusing the vehicle driving information collected from a vehicle areknown, and any one of the known weight estimation methods may beapplied.

According to the embodiment of the present disclosure, in the firstcontroller 20, the vehicle driving information required for the vehicleweight estimation may include a vehicle speed, acceleration, and a motortorque.

The vehicle speed and the acceleration of the vehicle drivinginformation required for the vehicle weight estimation are detected by adriving information detector 10 of the vehicle. The driving informationdetector 10 may include sensors detecting the vehicle speed and theacceleration.

A sensor of the driving information detector 10 detecting the vehiclespeed may be a wheel speed sensor 11 mounted to a vehicle wheel. It isknown that wheel speed and vehicle speed information can be obtainedfrom the signal of the wheel speed sensor 11.

For example, the signals of wheel speed sensors 11 mounted to aplurality of wheels in a vehicle may be used. In this case, when anaverage speed is obtained by averaging the rotational speeds (the wheelspeeds) of the wheels obtained from the signals of the wheel speedsensor 11, real-time vehicle speed information can be obtained from theaverage speed of the wheels.

In addition, a sensor of the driving information detector 10 detectingacceleration may be a vertical acceleration sensor 12 mounted to avehicle. In this case, the acceleration is real time verticalacceleration information of the vehicle detected by the verticalacceleration sensor 12.

The vertical acceleration detected by the vertical acceleration sensor12 is used to obtain the gradient information of a road on which avehicle currently drives, and the road gradient (a road slope angle, θ)information is used to estimate the weight of the vehicle.

Accordingly, the road gradient θ can be obtained by using the verticalacceleration information detected by the vertical acceleration sensor12, and in this case, can be obtained by further using vehicleacceleration. The vehicle acceleration can be obtained bydifferentiating the vehicle speed.

For example, the road gradient θ can be calculated by an equation“θ=1/g×(the vertical acceleration—vehicle acceleration)”. Here, g refersto gravitational acceleration.

Such a method of calculating the road gradient θ is merely an example,and the present disclosure is not limited thereto, and any method inwhich real-time gradient information of a road on which a vehicle iscurrently driving can be obtained may be applied.

For example, a road gradient information at a current vehicle positioncan be obtained from a GPS signal received through a GPS receiver of avehicle and 3D map information, and the weight of the vehicle can beestimated by using the road gradient information obtained in this case.

In addition, the motor torque of the driving information for the vehicleweight estimation may be a motor torque command used to control a drivemotor.

The vehicle driving information required to determine the motor torquecommand includes driving input information of a driver and the vehiclestate information. Here, the driving input information of the driver mayinclude an accelerator pedal input value (APS value) and a brake pedalinput value (BPS value), and the vehicle state information may includethe vehicle speed.

The vehicle driving information required to determine the motor torquecommand can be detected by the driving information detector 10 of avehicle. To this end, the driving information detector 10 may furtherinclude an accelerator pedal detector 14 detecting the accelerator pedalinput information according to the state of the accelerator pedalmanipulation by a driver, and a brake pedal detector 15 detecting thebrake pedal input information according to the state of the brake pedalmanipulation by the driver.

Here, the accelerator pedal detector 14 may be a known acceleratorposition sensor (APS) that is mounted to the accelerator pedal andoutputs an electrical signal according to the state of the acceleratorpedal manipulation by the driver.

Furthermore, the brake pedal detector 15 may be a known brake pedalsensor (BPS) which is mounted to a brake pedal and outputs an electricalsignal according to the state of the brake pedal manipulation by thedriver.

Finally, the first controller 20 can estimate the current weightinformation of a vehicle based on the real time driving information ofthe vehicle speed, the road gradient, and the motor torque command.Equation 1 below shows an example of a formula in which the vehicleweight can be estimated.

$\begin{matrix}{m = \frac{\int_{t0}^{tl}{\left\lbrack {{\frac{\eta_{RD}}{r_{tire}}\left( \tau_{Mot}^{BeAj} \right)} - \left( {f_{0} + {f_{1}\upsilon} + {f_{2}\upsilon^{2}}} \right)} \right\rbrack{dt}}}{\left\lbrack {{\Delta\upsilon} + {\int_{t0}^{tl}{{g{sin\theta}}\ {dt}}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

Here, m refers to vehicle weight, η_(RD) refers to efficiency of thereduction gear, and r_(tire) refers to a dynamic radius of a tire.

Furthermore, in Equation 1,

_(Mol) ^(BeAj) refers to the motor torque, which may be the motor torquecommand used to control the drive motor 41.

In addition, in Equation 1, fo, f1, and f2 refer to driving loads, vrefers to the vehicle speed, g refers to the gravitational acceleration,and θ refers to the road gradient.

Although the method and equation of estimating the vehicle weight aredescribed, the present disclosure is not limited to the weightestimation method and the above equation. Any known methods or equationsof accurately estimating vehicle weight may be applied to the presentdisclosure.

For example, the first controller 20 receives the value of theacceleration and can calculate the vehicle weight by using a vehicledriving force F and the value of the acceleration a In “F=m×a”, it ispossible to calculate m corresponding to the vehicle weight by using“F/a”.

In addition, as another example of estimating vehicle weight, a patentapplication entitled “Vehicle Weight Estimation Method by AccelerationSensor” (Korean Patent Application No. 10-2019-0158424, filed on Oct. 8,2019) was filed by the applicant of the subject application, and thisvehicle weight estimation method may be applied to the presentdisclosure.

In addition, in the present disclosure, a weight estimation prohibitioncondition may be set in the first controller 20, and the weightestimation prohibition condition may include a condition in which theroad gradient is at least a set value, and a condition in which asteering angle is at least a set angle.

That is, when the road gradient is at least the set value and thesteering angle is at least the set angle, the weight estimationprohibition condition is determined to be satisfied, so the firstcontroller 20 does not perform the vehicle weight estimation.Accordingly, the anti-jerk control in which an estimated vehicle weightis taken into consideration is not performed.

In this case, the existing motor control or anti-jerk control may beperformed without using the estimated vehicle weight.

Alternatively, when the weight estimation prohibition condition is notsatisfied, the vehicle weight estimation is performed, and then theanti-jerk control in which the estimated vehicle weight is taken intoconsideration is performed.

As described above, to determine whether the weight estimationprohibition condition is satisfied, the driving information detector 10may further include a steering angle sensor 16 detecting the steeringangle according to the state of the steering wheel manipulation by thedriver.

Meanwhile, as described above, the first controller 20 calculates therequired torque command of the driver in real time based on the drivinginput information of the driver and the vehicle state information duringvehicle driving. The driving input information of the driver may includethe accelerator pedal input value (APS value) and the brake pedal inputvalue (BPS value), and the vehicle state information may include thevehicle speed.

In the first controller 20, the required torque command can bedetermined based on the APS value and the BPS value of the driver whichreflect the demands of the driver, and a current vehicle speedinformation.

As provided herein, the process or method of calculating the requiredtorque command is not different from the process and method in which thevehicle control unit calculates the required torque command by using thedriving information of a vehicle collected in real time in a normalelectric vehicle, and is a known technology, so detailed descriptionthereof will be omitted.

Finally, as described above, the current vehicle weight estimated by thefirst controller 20 to and the required torque command calculatedthereby are transmitted to the second controller 30 in real time.

Referring to FIGS. 2A and 2B, it can be seen that a process in which thedriving information collected from a vehicle is input to the firstcontroller 20 and the second controller 30 at S11, a process in whichwhether the weight estimation prohibition condition is satisfied isdetermined in the first controller 20 at S12, a process in which whenthe weight estimation prohibition condition is not satisfied, thevehicle weight estimation is performed in the first controller 20 atS13, and a process in which the estimated vehicle weight and therequired torque command are output from the first controller 20 at S14are performed.

Prior to performing the anti-jerk control, the second controller 30determines whether the anti-jerk control can be currently performed,that is, whether an anti-jerk enable state is satisfied, based on thevehicle driving information at S12′. In this case, the vehicle drivinginformation may include gear information (P, R, N, and D gearinformation) and transaction control system (TCS) operation information.

Here, the gear information may be input from a shift controller (notshown) or a shift lever detector (not shown).

Although the shift lever detector is not shown in FIG. 1, when thesecond controller 30 is provided to receive the gear information (shiftlever position information) directly from the shift lever detector, thedriving information detector 10 of FIG. 1 further includes the shiftlever detector.

The shift lever detector detects the shift lever position information(P, R, N, and D gear information) according to the state of the shiftlever manipulation by the driver.

In the present disclosure, the second controller 30 determines that theanti-jerk enable state is not satisfied when a gear is a P gear, whichis a parking gear, or an N gear, which is a neutral gear, and does notperform the anti-jerk control.

In addition, during TCS operation, it is determined that the anti-jerkenable state is not satisfied, and the anti-jerk control is notperformed.

Alternatively, when a gear is not the P gear or the N gear, that is,when TCS is not operating while a current gear is a D gear, which is adriving gear, or an R gear, which is a rearward gear, it is determinedthat the anti-jerk enable state is satisfied.

When the anti-jerk enable state is determined to be satisfied asdescribed above, the second controller 30 determines an anti-jerk modeby using the current driving information of a vehicle at S13′.

In the present disclosure, for the effective control of the anti-jerk,the anti-jerk mode may be classified according to driving conditions.The anti-jerk mode is classified to differentiate the anti-jerk torqueaccording to the driving condition of a vehicle, and may be a modecorresponding to braking, acceleration, a constant speed, or ananti-jerk inhibition condition.

For example, in the present disclosure, the anti-jerk mode may includeat least two modes of an anti-jerk off mode (an “AJ 0” mode), a brakemode (an “AJ 1” mode), a tip-in mode (an “AJ 2” mode), and a tip-outmode (an “AJ 3” mode).

The anti-jerk off mode is a mode in which the anti-jerk control is off,and the brake mode is an anti-jerk mode of a time at which braking isperformed due to the driver's pressing of a brake pedal.

A case in which the anti-jerk control is off may be determined as a casein which a predetermined anti-jerk inhibition condition is satisfied, oras a case in which a current gear is the P gear which is a parking gear,or the N gear which is a neutral gear even in a case which does notcorrespond to the anti-jerk inhibition condition.

In addition, the tip-in mode is an anti-jerk mode (torque increase) of atime at which the driver tips in the accelerator pedal, and the tip-outmode is an anti-jerk mode (torque decrease) of a time at which thedriver tips out the accelerator pedal.

In the above description, the anti-jerk mode has been described toinclude a total of four modes, but this is merely an example, and thepresent disclosure is not limited thereto. The anti-jerk mode may bevariously changed in the type or number thereof, the definition of eachmode thereof, and a driving condition determined for each mode.

For example, in the present disclosure, the anti-jerk mode may include acreep mode in which the motor torque changes within a predeterminedrange for a set time instead of the anti-jerk off mode. In this case,the anti-jerk mode may include at least two modes of the brake mode, thetip-in mode, the tip-out mode, and the creep mode.

Next, when the anti-jerk mode is determined, the second controller 30determines the anti-jerk torque value in which the current vehicleweight is taken into consideration by using the estimated vehicle weightreceived from the first controller 20 at S14′ to S19, and next,determines a final motor torque command by compensating the requiredtorque command received from the first controller 20 with the anti-jerktorque at S20.

When the final motor torque command is determined as described above,the second controller 30 operates the inverter according to the motortorque command and controls the motor 41 at S21.

Referring to FIGS. 2A and 2B, to determine the anti-jerk torque value inwhich the vehicle weight is taken into consideration, in the secondcontroller 30, the model speed of the motor is calculated at S14′, speeddeviation between the model speed and actual speed of the motor iscalculated, and motor vibration value is obtained through the deviationbetween the model speed and actual speed of the motor at S15.

In addition, as described hereinafter, in the second controller 30, acurrent loading stage is determined through the estimated vehicle weightat S16, a dead zone corresponding to the determined anti-jerk mode andloading stage is determined, and whether the speed deviation is includedin the dead zone is checked at S17.

Next, when the speed deviation is not included in the dead zone, in thesecond controller to 30, a torque factor value corresponding to theanti-jerk mode and the loading stage is determined at S18, and then theanti-jerk torque value is determined by using the motor vibration valueand the torque factor value at S19.

The process of determining the anti-jerk torque will be described inmore detail as follows.

The anti-jerk torque is a torque preventing the vibration (shock & jerk)of a drivetrain which may occur during the speed increasing/decreasingof a vehicle. The anti-jerk torque of a motor-driven vehicle (anelectric vehicle) can be calculated by using the real-time drivinginformation of a vehicle. Here, the driving information may includeinformation on the wheel speed and a motor speed detected by sensors 11and 12, respectively.

In addition to the motor speed and the wheel speed, the accelerationvalue of a vehicle may be used. The acceleration, together with thewheel speed, may be used to calculate the model speed of the motor.

The motor speed is the rotational speed of the motor detected by a motorspeed sensor 13. In the anti-jerk control, the motor speed detected bythe motor speed sensor 13 is the actual speed of the motor.

The motor speed sensor 13 may be a normal resolver mounted to the motor41 (the drive motor) of an electric vehicle.

The wheel speed is the rotational speed of the wheel detected by thewheel speed sensor 11. The wheel speed is used to calculate the modelspeed of the motor, whereby in the second controller 30, the anti-jerktorque can be calculated based on the actual speed and model speed ofthe motor.

In the present disclosure, as described hereinafter, the anti-jerktorque according to the vehicle weight is obtained by further using theestimated vehicle weight obtained from the first controller 20.

In an electric vehicle (a motor-driven vehicle) in which the anti-jerkcontrol is performed, to the motor torque command for a motor controlmay be determined to be the sum value of the required torque commandaccording to the driver's demands and the anti-jerk torque for vibrationreduction as in Equation 2 below (S20 of FIG. 2B). This can be appliedeven to the present disclosure in the same way.

Motor torque command=Required torque command+Anti-jerktorque.  [Equation 2]

When calculating the anti-jerk torque, the model speed means the motorspeed at which vibration is ignored, and may mean an equivalent wheelspeed obtained by converting the wheel speed detected by the wheel speedsensor 11 into the speed of the motor 41 by using a gear ratio betweenthe motor and the wheel.

The model speed may be referred to as the value of a reference speedrequired for the anti-jerk control of the motor, and the anti-jerkcontrol is a control offsetting the speed fluctuation of the motor. Forsuch anti-jerk control, the reference speed is required to determine howmuch the motor speed fluctuation is.

Such model speed may be a speed calculated in reverse from the wheelspeed to a value related to the motor by using the wheel speed.

When calculating the model speed, in addition to the wheel speed, avehicle acceleration value may be further used to improve anti-jerkcontrol performance. Accordingly, the anti-jerk control can be performedin advance by predicting the change of the model speed calculated byusing the acceleration value.

Since such a calculation process of the model speed is also a technologyknown through the known anti-jerk control, the detailed descriptionthereof will be omitted in this specification.

The method of calculating the model speed includes a wheel speed-basedcalculation method, and a wheel speed estimation calculation method as amethod to use the anti-jerk more actively. During wheel speedestimation, the acceleration value is used.

Furthermore, as described above, in the present disclosure, theanti-jerk torque can be determined by the actual speed and model speedof the motor 41, and value corresponding to the estimated vehicle weight(that is, the estimated vehicle weight of the first controller) in thesecond controller 30.

More particularly, when a current motor speed (that is, the currentactual speed of a motor) is detected by the motor speed sensor 13, andthe current model speed of the motor based on the wheel speed detectedby the wheel speed sensor 11 is obtained, the anti-jerk torque can becalculated based on the model speed and actual speed of the motor, andthe estimated vehicle weight of the first controller.

In the present disclosure, the anti-jerk torque may be determined to bevalue corresponding to the deviation between the model speed and actualspeed of the motor. The motor vibration value can be obtained by usingthe deviation between the model speed and actual speed of the motor, andthe anti-jerk torque value is determined based on the motor vibrationvalue.

In this case, the anti-jerk torque value can be calculated bymultiplying the motor vibration value by the torque factor value. Here,the torque factor value is determined according to the current vehicleweight (the estimated vehicle weight).

In the present disclosure, the process and method of obtaining the motorvibration value by using the deviation between the model speed andactual speed of the motor is not different from the known process andmethod of obtaining the motor vibration value, and the motor vibrationvalue may be determined by the known calculation process and method.

Meanwhile, in the present disclosure, for the effective control of theanti-jerk, the anti-jerk mode may be classified into several modesaccording to driving conditions. The anti-jerk mode is classified todifferentiate the anti-jerk torque according to the driving condition ofa vehicle, and may be a mode corresponding to braking, acceleration, aconstant speed, or an anti-jerk inhibition condition.

For a specific example, in the present disclosure, the anti-jerk modemay include the anti-jerk off mode (the “AJ 0” mode), the brake mode(the “AJ 1” mode), the tip-in mode (the “AJ 2” mode), and the tip-outmode (the “AJ 3” mode).

The anti-jerk off mode is an anti-jerk mode in which the anti-jerkcontrol is off, and the brake mode is an anti-jerk mode of a time atwhich braking is performed due to the driver's pressing a brake pedal.

In addition, the tip-in mode is the anti-jerk mode (torque increase) ofa time at which the driver tips in the accelerator pedal, and thetip-out mode is the anti-jerk mode (torque decrease) of a time at whichthe driver tips out the accelerator pedal.

In the above description, the anti-jerk mode has been described toinclude a total of four modes, but this is merely an example, and it isnoted that the present disclosure is not limited thereto. The anti-jerkmode may be variously changed in the type or number thereof, thedefinition of each mode thereof, and the driving condition determinedfor each mode.

In addition, in the present disclosure, an anti-jerk dead zone may beset, and is a speed section in which the anti-jerk control is not usedbased on the speed deviation between the model speed and actual speed ofthe motor. The anti-jerk dead zone can be set based on the speeddeviation for each anti-jerk mode.

In this case, the minimum speed and the maximum speed of a speeddeviation range corresponding to the dead zone for each anti-jerk modeare predetermined, and a speed section between the minimum speed and themaximum speed set for each anti-jerk mode is a dead zone for each modein which the anti-jerk is off.

In the present disclosure, the dead zone is an anti-jerk off sectionthat is set to prevent an anti-jerk malfunction caused by disturbance atthe extremely low speed of the motor.

In addition, the anti-jerk control is fundamentally applied in themotor-driven vehicle to solve a problem such as the vibration of adrivetrain caused by the fluctuation of the motor speed. While the motorspeed is fluctuating, the anti-jerk torque is required to be applied tothe vehicle to prevent such a problem.

However, under normal driving conditions, the motor speed fluctuationseldom occurs or disappears because the vehicle weight has changed.Typical cases affected by the change of the vehicle weight include acase in which a vehicle starts from a stationary state, and a case inwhich a vehicle operates at low speed.

In the case that a vehicle is heavy, when the driver inputs theintention to start the vehicle and transmits the intention to thevehicle, that is, when there is driving input for starting the vehicle,motor speed increases, but the vehicle is heavy and may not move.

Such a phenomenon occurs for a longer time before a vehicle wheel reallymoves compared to when a vehicle is light. In this case, the motor speedfluctuates.

In addition, when a vehicle is heavy, the torque factor value applied tothe anti-jerk torque is increased such that the motor speed fluctuationis suppressed. The same is true when road traffic is heavy,particularly, when a vehicle drives at low speed by starting from anuphill road or when a vehicle moves backwards on a downhill road.

Accordingly, the torque factor value in which the vehicle weight istaken into consideration is required to be used when calculating theanti-jerk torque. Accordingly, in the present disclosure, the torquefactor value corresponding to the current vehicle weight is determinedand used to calculate the anti-jerk torque.

To this end, in the present disclosure, the second controller 30 isprovided to determine the anti-jerk mode corresponding to a currentdriving condition through the driving information of a vehicle, and todetermine the current loading stage of a vehicle by using a currentvehicle weight value estimated by the first controller 20, that is, theestimated vehicle weight of the first controller.

In addition, the second controller 30 determines whether the speeddeviation between the model speed and actual speed of the motor 41corresponds to the current loading stage and the anti-jerk dead zone setin the anti-jerk mode.

When the second controller 30 determines that the speed deviationcorresponds to the anti-jerk dead zone, the second controller 30 doesnot perform the anti-jerk control by maintaining the anti-jerk controlin an inactive state.

Alternatively, when the second controller 30 determines that the speeddeviation does not correspond to the anti-jerk dead zone, the secondcontroller 30 performs the anti-jerk control. In this case, the torquefactor value corresponding to the current loading stage and theanti-jerk mode is determined, and the anti-jerk torque is calculated bymultiplying the motor vibration value corresponding to the speeddeviation between the model speed and actual speed of the motor by thetorque factor value.

In the present disclosure, a vehicle weight range is divided into aplurality of sections such that the current loading stage of a vehiclecan be determined by the second controller 30 based on the vehicleweight estimated by the first controller 20, and then the loading stageof the vehicle is determined in advance for each divided section. Theinformation of a weight section for each loading stage is input to thesecond controller 30 and is set therein.

In the second controller 30, a plurality of loading stages havingdifferent vehicle weight ranges are set. For example, the entire weightrange of the vehicle, which can be changed when boarding a passenger orloading cargo, including an empty state of a vehicle may be divided intoa total of four stages: an empty stage, a first loading stage, a secondloading stage, and a third loading stage.

In this case, in the vehicle weight, the third loading stage may be setas the largest weight section, the second loading stage may be set asthe next largest weight section, and the first loading stage may be setas the smallest weight section except for the empty state.

The weight section corresponding to each loading stage may varydepending on the characteristics of an applied vehicle, and each loadingstage is not determined as a specific weight section.

In addition, the loading stage corresponding to the current weight valueis determined by the second controller 20 based on the vehicle weightvalue estimated by the first controller 20. In this case, in order toprevent frequent changes in the loading stages, hysteresis havingdifferent boundary values for the entry and exit of each loading stage,the boundary values dividing each loading stage, is preferably set.

Table 1 below shows a map in which the torque factor value is set foreach anti-jerk mode when the loading stage of the vehicle is in an emptystate, and Table 2 and Table 3 show a map in which a dead zone minimumspeed is set for each anti-jerk mode, and a map in which a dead zonemaximum speed is set for each anti-jerk mode, respectively, when theloading stage of the vehicle is in an empty state.

TABLE 1 Anti-jerk (AJ) mode 0 1 2 3 . Torque factor 0 0.3 0.2 . .

TABLE 2 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 −7 −5 . .

TABLE 3 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 7 5 . .

According to the examples of Table 2 and Table 3, when the speeddeviation (rpm), which is difference value between the model speed andactual speed of the motor, is between minimum speed −7 and maximum speed7 (dead zone is −7 to 7 rpm) in a case in which a vehicle is empty andthe anti-jerk mode is the brake mode (“AJ 1”), the anti-jerk control isnot performed and is off.

In addition, according to the examples of Table 2 and Table 3, when thespeed deviation (rpm) is between minimum speed −5 and maximum speed 5(dead zone is −5 to 5 rpm) in the case in which the vehicle is empty andthe anti-jerk mode is the tip-in mode (“AJ 2”), the anti-jerk control isnot performed and is off.

Furthermore, according to the example of Table 1, in the case in whichthe vehicle is empty, the torque factor value is determined to be 0.3 inthe case of the brake mode, and the torque factor value is determined tobe 0.2 in the case of the tip-in mode.

Next, Table 4 below shows a map in which the torque factor value is setfor each anti-jerk mode when the loading stage of a vehicle is the firstloading stage, and Table 5 and Table 6 show a map in which the dead zoneminimum speed is set for each anti-jerk mode, and a map in which thedead zone maximum speed is set for each anti-jerk mode, respectively, inthe case of the first loading stage.

TABLE 4 Anti-jerk (AJ) mode 0 1 2 3 . Torque factor 0 0.3 0.3 . .

TABLE 5 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 −5 −5 . .

TABLE 6 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 7 5 . .

In the present disclosure, the torque factor value and the dead zone aredetermined by the maps, that is, a map in which the torque factor valueis set according to the loading stage and the anti-jerk mode, and a mapin which the minimum speed and the maximum speed of the dead zone areset for each anti-jerk mode. The maps are previously input to and storedin the second controller 30 to be used.

According to the examples of Table 5 and Table 6, when the speeddeviation (rpm) is between the minimum speed −5 and the maximum speed 7(the dead zone is −5 to 7 rpm) in a case in which the estimated vehicleweight corresponds to the first loading stage, and the anti-jerk mode isthe brake mode (“AJ 1”), the anti-jerk control is not performed, and isoff.

In addition, according to the examples of Table 5 and Table 6, when thespeed deviation (rpm) is between the minimum speed −5 and the maximumspeed 5 (the dead zone is −5 to 5 rpm) in a case in which the estimatedvehicle weight corresponds to the first loading stage, and the anti-jerkmode is the tip-in mode (“AJ 2”), the anti-jerk control is notperformed, and is off. Furthermore, according to the example of Table 4,in the first loading stage, the torque factor value is determined to be0.3 in the case of the brake mode, and the torque factor value isdetermined to be 0.3 even in the case of the tip-in mode.

Next, Table 7 below shows a map in which the torque factor value is setfor each anti-jerk mode when the loading stage of a vehicle is thesecond loading stage, and Table 8 and Table 9 show a map in which thedead zone minimum speed is set for each anti-jerk mode, and a map inwhich the dead zone maximum speed is set for each anti-jerk mode,respectively, in the case of the second loading stage.

TABLE 7 Anti-jerk (AJ) mode 0 1 2 3 . Torque factor 0 0.4 0.3 . .

TABLE 8 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 −3 −3 . .

TABLE 9 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 7 5 . .

According to the examples of Table 8 and Table 9, when the speeddeviation (rpm) is between the minimum speed −3 and the maximum speed 7(the dead zone is −3 to 7 rpm) in a case in which the estimated vehicleweight corresponds to the second loading stage, and the anti-jerk modeis the brake mode (“AJ 1”), the anti-jerk control is not performed, andis off. In addition, according to the examples of Table 8 and Table 9,when the speed deviation (rpm) is between the minimum speed −3 and themaximum speed 5 (the dead zone is −3 to 5 rpm) in a case in which theestimated vehicle weight corresponds to the second loading stage, andthe anti-jerk mode is the tip-in mode (“AJ 2”), the anti-jerk control isnot performed, and is off.

In addition, according to the example of Table 7, in the second loadingstage, the torque factor value is determined to be 0.4 in the case ofthe brake mode, and the torque factor value is determined to be 0.3 inthe case of the tip-in mode.

Next, Table 10 below shows a map in which the torque factor value is setfor each anti-jerk mode when the loading stage of a vehicle is the thirdloading stage, and Table 11 and Table 12 show a map in which the deadzone minimum speed is set for each anti-jerk mode, and a map in whichthe dead zone maximum speed is set for each anti-jerk mode,respectively, in the case of the third loading stage.

TABLE 10 Anti-jerk (AJ) mode 0 1 2 3 . Torque factor 0 0.5 0.4 . .

TABLE 11 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 −2 −2 . .

TABLE 12 Anti-jerk (AJ) mode 0 1 2 3 . Speed deviation (rpm) 0 7 5 . .

According to the examples of Table 11 and Table 12, when the speeddeviation (rpm) is between minimum speed −2 and a maximum speed 7 (thedead zone is −2 to 7 rpm) in a case in which the estimated vehicleweight corresponds to the third loading stage, and the anti-jerk mode isthe brake mode (“AJ 1”), the anti-jerk control is not performed, and isoff.

In addition, according to the examples of Table 11 and Table 12, whenthe speed deviation (rpm) is between the minimum speed −2 and themaximum speed 5 (the dead zone is −2 to 5 rpm) in a case in which theestimated vehicle weight corresponds to the third loading stage, and theanti-jerk mode is the tip-in mode (“AJ 2”), the anti-jerk control is notperformed, and is off.

Furthermore, according to the example of Table 10, in the third loadingstage, the torque factor value is determined to be 0.5 in the case ofthe brake mode, and the torque factor value is determined to be 0.4 evenin the case of the tip-in mode.

In Table 1 to Table 12, “•” does not mean 0 (zero), but means anarbitrary number.

As can be seen from Table 1 to Table 12, in the present disclosure, thetorque factor value for determining the anti-jerk torque for eachloading stage, and the speed deviation range of the dead zone in whichthe anti-jerk control is off are set in advance, and further, the torquefactor value and the speed deviation range of the dead zone for eachanti-jerk mode are set in advance.

The values in Table 1 to Table 12 are exemplary, and the presentdisclosure is not limited thereto. The anti-jerk mode, the torque factorfor each loading stage, the speed deviation range of the dead zone, andthe minimum speed and maximum speed of the dead zone may be properlychanged and tuned according to vehicle characteristics.

When the anti-jerk torque is excessively applied in the case that avehicle is relatively light, unnecessary vibration may be applied to thedrivetrain. Accordingly, as the vehicle weight corresponds to a lowerloading stage, the torque factor value may be set to be lower, and thespeed deviation range corresponding to the dead zone may be set as awider range.

In addition, as the vehicle weight corresponds to a higher loadingstage, the torque factor value may be set to be higher, and the speeddeviation range corresponding to the dead zone may be set as a narrowerrange.

Each value in Table 1 to 12 may be changed according to vehiclecharacteristics, and thus is required to be set based on data obtainedfrom conducting preliminary tests and evaluations for associatedvehicles.

For example, the speed deviation range of the dead zone may be set to bewider or narrower according to the characteristics of the anti-jerkmode.

Furthermore, the reason why the dead zone is differentiated according tothe vehicle weight (the loading stage) as described above is that thereare times at which the anti-jerk control is required to be activelyperformed when the weight is heavy. When the anti-jerk control isactively performed, the absolute value of the minimum speed and themaximum speed of the dead zone is set to be small, and the speeddeviation range of the dead zone in which the anti-jerk control is notperformed and is off is reduced.

Although the exemplary embodiment of the present disclosure has beendescribed in detail, the scope of the claims of the present disclosureis not limited thereto, and those skilled in the art will appreciatethat various modifications, additions, and substitutions are possible,without departing from the scope and spirit of the disclosure asdisclosed in the accompanying claims.

What is claimed is:
 1. An anti-jerk control method for an electricvehicle, the method comprising: estimating vehicle weight by acontroller based on vehicle driving information collected from avehicle; determining a required torque command of a driver by thecontroller based on the vehicle driving information collected from thevehicle; determining, by the controller, anti-jerk torque according tothe vehicle weight based on calculated speed deviation and the estimatedvehicle weight information after calculating the speed deviation betweena model speed and an actual speed of a motor; and controlling, by thecontroller, a drive motor according to a compensated motor torquecommand by compensating the required torque command with the anti-jerktorque.
 2. The method of claim 1, wherein a weight estimationprohibition condition is set in the controller, the weight estimationprohibition condition comprising a condition in which a gradient of aroad on which the vehicle drives is at least a set value, and acondition in which a steering angle is at least a set angle, whereinestimating the vehicle weight, determining the required torque command,determining the anti-jerk torque, and controlling the drive motor areperformed only when the weight estimation prohibition condition is notsatisfied.
 3. The method of claim 1, further comprising: determining, bythe controller, an anti-jerk mode corresponding to a current drivingcondition in a plurality of anti-jerk modes preset from the drivinginformation collected from the vehicle, wherein in determining theanti-jerk torque according to the vehicle weight, a motor vibrationvalue is obtained through the calculated speed deviation, a torquefactor value is determined through the estimated vehicle weight and thedetermined anti-jerk mode, and the anti-jerk torque is determinedthrough the obtained the motor vibration value and the determined torquefactor value.
 4. The method of claim 3, wherein in the controller, whena plurality of loading stages having different vehicle weight ranges areset, and a loading stage corresponding to the estimated vehicle weightis determined, the torque factor value corresponding to the determinedanti-jerk mode and the loading stage is determined.
 5. The method ofclaim 4, wherein the torque factor value is determined, by thecontroller, through a map in which the torque factor value is setaccording to the anti-jerk mode and the loading stage.
 6. The method ofclaim 4, wherein, in the controller, the anti-jerk mode and a dead zonewhich is a speed deviation range in which anti-jerk control is off foreach loading stage are set in advance, and when the speed deviationcalculated through the model speed and actual speed of the motor isincluded in a speed deviation range of a dead zone corresponding to acurrent anti-jerk mode and loading stage, determining the anti-jerktorque according to the vehicle weight, and controlling the drive motoraccording to the compensated motor torque command are not performed. 7.The method of claim 6, wherein, in the controller, the speed deviationrange of the dead zone corresponding to the current anti-jerk mode andloading stage is determined to be used by using a map in which theanti-jerk mode, and minimum speed and maximum speed of the speeddeviation range for each loading stage are set.
 8. The method of claim6, wherein as a set vehicle weight of the plurality of loading stagescorresponds to a higher loading stage, the speed deviation range of thedead zone is set as a narrower range.
 9. The method of claim 6, whereinas a set vehicle weight of the plurality of loading stages correspondsto a higher loading stage, the torque factor value is set as a highervalue.
 10. The method of claim 3, wherein the plurality of anti-jerkmodes includes at least two modes of a brake mode of a time at which thedriver steps on a brake pedal, a tip-in mode of a time at which thedriver tips in an accelerator pedal, a tip-out mode of a time at whichthe driver tips out the accelerator pedal, and a creep mode in whichmotor torque changes within a predetermined range for a set time. 11.The method of claim 1, wherein, in the controller, a plurality ofloading stages having different vehicle weight ranges is set; indetermining the anti-jerk torque according to the vehicle weight, amotor vibration value is obtained by using the calculated speeddeviation; when a loading stage corresponding to the estimated vehicleweight is determined, a torque factor value corresponding to thedetermined loading stage is determined; and the anti-jerk torque isdetermined by using the obtained the motor vibration value and thedetermined torque factor value.
 12. The method of claim 11, wherein, inthe controller, a dead zone which is a speed deviation range in whichanti-jerk control is off for each loading stage is set in advance, andwhen the speed deviation calculated by using the model speed and actualspeed of the motor is included in the speed deviation range of the deadzone corresponding to a current loading stage, the anti-jerk control isinactive in the controller.
 13. The method of claim 12, wherein as a setvehicle weight of the plurality of loading stages corresponds to ahigher loading stage, the speed deviation range of the dead zone is setas a narrower range.
 14. The method of claim 12, wherein as a setvehicle weight of the plurality of loading stages corresponds to ahigher loading stage, the torque factor value is set as a higher value.15. A non-transitory computer readable medium containing programinstructions executed by a processor, the computer readable mediumcomprising: program instructions that estimate vehicle weight based onvehicle driving information collected from a vehicle; programinstructions that determine a required torque command of a driver basedon the vehicle driving information collected from the vehicle; programinstructions that determine anti-jerk torque according to the vehicleweight based on calculated speed deviation and the estimated vehicleweight information after calculating the speed deviation between a modelspeed and an actual speed of a motor; and program instructions thatcontrol a drive motor according to a compensated motor torque command bycompensating the required torque command with the anti-jerk torque.